1. Field of the Invention
The present invention relates to a scroll-type compressor. More particularly, the present invention relates to a scroll-type compressor with an integrated motor that compresses gases to be supplied to a fuel cell.
2. Description of the Related Art
Recently, a demand for the electric cars are increasing because of the requirement to save petroleum resources. A fuel cell, the power source to propel an electric car, has a high energy conversion efficiency and its reaction products such as water and carbon dioxide are not noxious and are environment-friendly, therefore, a demand for the application thereof are expected to increase. A scroll-type compressor, which can easily be made compact and light, is appropriate to supply the compressed gases to a fuel cell.
From the standpoint of saving energy, it is preferable that the rise in temperature of the air is restricted so that the work load of a scroll-type compressor is as small as possible. Therefore, in the conventional method, a cooling chamber, which circulates cooling water around a high pressure chamber, is provided, heat is exchanged between the air in the high pressure chamber as well as air during compression and the low temperature cooling water, whereby a rise in air temperature can be suppressed and the work Load of the compressor reduced, as in the scroll-type compressor disclosed in Japanese Unexamined Patent Publication (Kokai) No.8-247056.
FIG. 5 is an axial cross-sectional view of a conventional scroll-type compressor. A housing 1, which is the outer shell of a conventional compressor, comprises a front casing 2, on the small-diameter side end face of which a recess is formed, an end plate 20 installed on the small-diameter side end face of the front casing 2, and a rear casing 3 installed on the large-diameter side end of the front casing 2.
A fixed scroll 21 is formed in the axial direction on the large-diameter side of the front casing 2. A suction portion 22 is formed on the outer circumferential side of the fixed scroll 21, and a discharge portion 23 is formed in the center of the inner circumferential side. A disc-shaped discharge valve 24 and a high pressure chamber 25 are formed on a discharge port 20a side of the discharge portion 23.
One end of a crank-shaped drive shaft 30 is arranged on the small-diameter side end of the rear casing 3, with rotation being possible. A movable plate 32, with a movable scroll 31 formed in the axial direction, is arranged on the other end of the drive shaft 30, with rotation being possible.
When the drive shaft 30 rotates and the movable scroll 31 orbits, a space enclosed by the fixed scroll 21 and the movable scroll 31 moves toward the center of the fixed scroll 21 while being compressed, therefore, the air in the space is gradually compressed. The compressed air arrives at the discharge portion 23, flows into the high pressure chamber 25 through the discharge valve 24, and is discharged to the outside of the compressor from the discharge port 20a. 
Cooling water flows into a cooling chamber 26 through a cooling water inflow port, which is not shown. The cooling chamber 26 is contiguous to the high pressure chamber 25 and a border surface 2a, through which the heat of the compressed air is transmitted. Therefore, heat is transmitted from the high-pressure air in the high pressure chamber and that during compression to the cooling water. The cooling water, to which heat is transmitted and whose temperature is raised, flows out of the compressor through the cooling water outflow port, which is not shown.
In a conventional scroll-type compressor, high-pressure air and air during compression are cooled to make the compression process as near as possible an isothermal compression so that the work load of the compressor is reduced.
On the other hand, a scroll-type compressor needs a drive means such as a separate motor. A scroll-type compressor with an integrated motor, which combines a compressor and a motor together, enables the whole compression system including a motor to be made compact. Because of this, the scroll-type compressor with an integrated motor is in particular appropriate as a compressor to supply gases, to a fuel cell, which is in a restricted space. The scroll-type compressor with an integrated motor also needs to release heat generated by components, such as a rotor, that rotate at high speed in the motor portion. Therefore, in addition to a cooling chamber in the compressor portion, a cooling means such as a fan was conventionally provided in the motor portion.
A conventional scroll-type compressor with an integrated motor, however, has the following problem. As described above, in a conventional scroll-type compressor with an integrated motor, two cooling means are provided separately in the motor portion and in the compressor portion (a cooling chamber), respectively. Therefore, equipment supporting the cooling means, such as a cooling water circuit in the cooling chamber and a power circuit of the fan, are provided separately, resulting in a large installation space requirement.
The present applicant has attained knowledge that the installation space can be reduced by providing cooling chambers in both the compressor portion and the motor portion as cooling means and by sharing the supporting equipment, such as a cooling circuit, for each cooling chamber.
Before this knowledge can be applied to a compressor for a fuel cell, however, the following problem must be solved. When gases are supplied to a fuel cell, they must be humidified to a certain extent. Therefore, a water vapor exchange film, to humidify discharged gases, is provided in the vicinity of the discharge port of the compressor portion. The water vapor exchange film can resist a temperature of around 140xc2x0 C. Therefore, it is necessary to lower the temperature of the discharged gases to below this temperature by means of a cooling chamber in the compressor portion. On the other hand, the motor portion can resist a temperature of around 170xc2x0 C. Therefore, it is necessary to lower the temperature of the motor portion to below this temperature by means of the cooling chamber in the motor portion.
When the cooling circuit is shared, however, the cooling efficiency is better in the cooling chamber to which the cooling fluid is supplied first, of the two cooling chambers, because the temperature of the cooling fluid is low. As a result, the cooling efficiency is worse in the cooling chamber to which the cooling fluid is supplied secondly.
After the above-mentioned knowledge and the application of this knowledge to a scroll-type compressor with an integrated motor for a fuel cell had been researched attentively by the present applicant, it was determined that the temperature of the water vapor exchange film and the motor portion can be lowered to below the resistance temperatures by providing each of the motor portion and the compressor portion with a cooling chamber as a cooling means, respectively, by arranging a single cooling circuit, as supporting equipment, to connect these cooling chambers and to supply the cooling fluid, and by making the cooling fluid flow in the cooling circuit in the direction from the cooling chamber of the compressor portion to that of the motor portion.
The scroll-type compressor with an integrated motor of the present invention has been completed based on the above-mentioned knowledge, and the object is to provide a compressor that requires a reduced installation space, decreases the work load of the compressor, and can resist the required temperature in operation.
To solve the above-mentioned problems, the scroll-type compressor with an integrated motor of the present invention comprises a housing, a fixed scroll fixed to the housing, a movable scroll, which is installed eccentrically to the fixed scroll in the housing and orbits with respect to the fixed scroll, and a motor portion, which is installed in the housing and drives the movable scroll; and is characterized in that the housing has a high pressure chamber into which gases compressed by the fixed scroll and the movable scroll are supplied, a first cooling chamber installed contiguous to the high pressure chamber and to which a cooling fluid is supplied, a second cooling chamber, which cools the motor portion and is supplied with cooling fluid, and a fluid passage, which connects the first cooling chamber and the second chamber and flows the cooling fluid in the direction from the first cooling chamber to the second cooling chamber.
In other words, the scroll-type compressor with an integrated motor of the present invention is characterized in that a first cooling chamber, to which the cooling fluid is supplied, is installed contiguous to the high pressure chamber of the compressor portion, a second cooling chamber, to which the cooling fluid to cool the motor portion is supplied, is provided separately from the first cooling chamber, and a fluid passage that passes the cooling fluid in the direction from the first cooling chamber to the second cooling chamber, is provided.
By installing the first cooling chamber contiguous to the high pressure chamber, gases can be cooled because heat is transferred from the discharged gas and the gas under compression to the cooling fluid in the first cooling chamber and, therefore, the work load of the compressor portion can be reduced. Moreover, by cooling the discharged gas to below the temperature the water vapor exchange film can resist, the water vapor exchange film, of low heat resistance, can be protected.
Moreover, by installing the second cooling chamber, the motor portion can be cooled with the compressor portion, because heat is transferred from the motor portion to the cooling fluid in the second cooling chamber. Because the motor portion is composed of densely arranged components such as iron cores and coils and is hermetically sealed, heat is easily generated and removal of heat is unlikely to take place. By installing the second cooling chamber, the temperature of the motor portion can be lowered and burning in the motor portion can be suppressed.
Furthermore, by connecting the first cooling chamber and the second cooling chamber with a fluid passage and flowing the cooling fluid from the first cooling chamber to the second cooling chamber, the motor portion and the water vapor exchange film installed together in the compressor portion can be effectively cooled to below the resistance temperature.